Method and apparatus for shutting off water intrusion through perforated casings



SePt- 15, l936 o. P. YoWELl.

METHOD AND APPARATUS FOR SHUTTING-OFF WATER INTRUSION THROUGH PERFORATEDCASINGS Filed April 20, 1956 2 Sheets-Sheet l MMIII..

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2 Sheets-Sheet 2 P. YOWELL Filed April 20, 1956 METHOD AND APPARATUS FORSHUTTING-OFF WATER INTRUSION THROUGH PERFORATED CASINGS Sept. 15, 1936.

Patented Sept. 15, 1936 METHOD AND APPARATUS Foa sHUTTrNG oFF WATERINTnUsroN THROUGH PEB.- FoaATED cAsmcs olneyP.Yowe11,wmmer,cauf.,assignor to o. P. i

Yowell Service Company, a corporation of California Application April20, 1936, Serial No. 75,351

13 Claims. (Cl. 16B-21) This invention has to do in a general waywithoil well operations and is primarily concerned with an improved methodAand apparatus for shutting off water intrusion through the perforatedcasing in an oil well.

As is well known to those familiar with the art, it frequently happensin oil well practice that the perforated casing which is situated in theoil zone or oil sand and through which the oil is received for removalfrom the well, may be located in a zone which in addition to the oilsand contains a stratum of water sand from which Water enters theperforated casing to contaminate the oil.

Various types of electrical, chemical and photoelectric apparatus havebeen devised for locating the regions of water intrusion and afterlocating such region of water intrusion it is the usual practice toattempt to fill the perforations in the region of the formationsurrounding this zone of intrusion with cement. It frequently happensthat after this is done it is found that the contamination of the oilwith the water continues and the reason for this, I have discovered, isthat the small strainer perforations in the casing in the region wherethey are exposed to Water soon become corroded, forcing the water tomigrate from the Water stratum up into the oil stratum so that itactually enters the perforated casin'g at a point spaced remotely fromthe actual water zone. It therefore becomes a primary object of thisinvention to devise a method of the class described which mayincorporate as an initial step a procedure whereby the actual waterstratum which is the sourcev of the contamination, may be accuratelylocated.

In view of the fact that the perforations or vstrainer openings in theperforated casing are comparatively small, and further in view of thenecessity of obtaining the maximum penetration l of cement into theformation in order to obtain a positive shut-off of water, my inventioncontemplates as an additional step under circumstances Where theperforations are small, the formation of new large perforations in thewall of the casingbefore the placement of cement therein.

In order to obtain the maximum penetration of cement into the formation,my invention con templates as a further step the discharge of suchcement in the region or zone to be cemented under a substantial pressureand t safeguard against the migration of appreciable amounts of cementslurry beyond the objective zone of cementation due to pressuredifferences inherent in the formation or due to the pressure under whichthe cement is actually applied, my invention contemplates the initialplacement of cement bridges at the two extremities of the water zone,such bridges extending out into the formation so as to provide apositive seal between the outer surface of the perforated casing and thesurroundlng formation at the two extremities of the lwater zone.

The bridge referred to above becomes particularly important inconnection with the upper end of the zone to be cemented since it isimportant that the return of cement into the perforated casing aroundthe cement discharging apparatus be prevented.

Further, to prevent the possibility of cement slurry returning to theperforated casing in the region of the water zone above the point ofdelivery and thereafter rising in the perforated casing into the regionabove the water zone, it becomes a further object of this invention toprovide a cement discharging apparatus which is equipped with sealing orpacking means surrounding the cement discharge conduit and positioned soas to always maintain a seal between the cement discharge conduit andthe interior of the perforated casing in the region of the upper bridge.

My invention also contemplates a novel form of cement dischargingapparatus equipped with packing means for the purpose referred to aboveand also equipped with a valve whereby the fluid in the casing may beby-passed up through the cement delivery tubing during the installationof the tool in the well.' This valve is equipped with means forpositively closing the same after the pressure discharge of cement hasbeen made whereby the pressure may be held on the cement so applied andback circulation may be set up through that portion of the casing abovethe tool in order to insure the removal of any cement slurry which mayhave leaked past the tool into the region thereabove. In this connectionmy invention contemplates a tool which is equipped with an inwardlyopening check valve in the cement delivery pipe through which such backcirculation may be maintained.

The details in the procedure contemplated by this invention as well ascertain details in the construction of a preferred form of apparatus foruse in connection therewith will be best understood from the followingdescription of the accompanying ldrawings which are chosen forillustrative purposes only and in which,

Fig. 1 is a sectional elevation of more or less diagrammatic character,illustrating a perforated casing in an oil well and further showing themanner in which corrosion is set up in the perforations of that portionof the casing which occupies the water zone or stratum;

Fig. 2 is a sectional elevation similar to Fig. 1 illustrating the stepof cleaning the corroded perforations;

Fig. 3 is a sectional elevation illustrating the step of formingenlarged perforations in the casing for the discharge of cement from thecasing into the formation;

Fig. 4 is a sectional elevation illustrating a casing which has beencleaned and perforated and further illustrating the results '0f theinitial operation followed in a preferred procedure of placing bridgesat` the two extremities of the water zone;

Fig. 5 is a sectional elevation which shows the cement plug containedwithin the casing at the region of the upper bridge as having beenremoved whlch is the condition present in the casing just prior to thefinal cementing operation; Fig. 6 is a sectional elevation illustratingthe final cementing operation and a preferred form of apparatus whichmay be employed in effecting this operation;

Fig. 7 is a sectional elevation illustrating the final result of myprocess, the cement contained within the casing having beendrilledtherefrom to leave an impervious wall in the region of the casingwhich occupies the water sand or zone; and

Fig. 8 is a sectional elevation illustrating a 'modified form of cementdischarging apparatus.

More particularly describing the invention as herein illustrated andreferring ilrst to Fig. 1 which, as pointed out above, illustrates aportion of a perforated oil well casing contained in a water sand orwater zone, reference numeral li indicates a bore hole or well whichcontains a casing vI2 provided with the ordinary slots or screenperforations indicated at I3. Reference numeral I4 indicates a watersand or water zone which is shown as being between two oil sandsindicated at l5 and I5.

It will be observed that the perforations in the casing whicharesituated in the region of the water zone have accumulated corrosivematter so that they are plugged as indicated by reference numeral I6.These perforations being plugged, cause the water in the zone Ily tomigrate in opposite directions along the walls of the bore hole asindicated at I1 and I1' so that the water may enter the perforatedcasing at a substantial distance from the zone or region in which it hasits source. It will thus be seen that if an attempt is made to locatethe Aposition of the water sand with any of the conventional waterlocating means which are lowered within the casing, with a casing suchas is shown in Fig. 1,`

of the' formations surrounding the casing at the.

point of iluid'entry.

Various types of apparatus may be employed further movement. y ment ofthe tubing 20 with its packers 23 and 35 closed off with enlargedperforationsjthrough acuesta for effecting Athis washing operation. Inother words, any of the conventional pressure or suction perforationwashers may be used. For the purpose of illustrating this step in theprocess of my invention I have shown in Fig. 2 a washing 5 apparatuswhich simultaneously combines pressure and suction in two adjacent zonesofthe formation. Since the detailsin the construction and operation ofthis washer form nopart of the present invention, I 'will make no.attempt 10 to describe its structural details. However, for purposes ofclarity the washer may be described as consisting in a general way of ahollow man'- drel or tubing 20 suspended through the medium of a tubing2| from the surface of the ground. 15` The lower end of the tubing 20 is.shown as be-` ingl provided with a guide shoe 22 and such tubing isprovided at extreme end portions with packing members 23 and 24 whichare rigidly mounted thereon. The intermediate portion of 20 the tubingslidably extends through a sleeve section 25 which is equipped with a.slip assembly 26 associated with an anchor member 21 adapted to guidethe slips thereon, the sleeve 25 also carrying a packer or a pluralityof packers indi- 25 cated generally by reference numeral 2l. When thisassembly is lowered into the desired position within the perforatedcasing the slip assembly is released through the medium of a bayonetlock 28 so that the further application of weight 30 causes'the slips toexpand into engagement with the inner surface of the casing therebylocking the sleeve 25 and its associated packer against Continueddownward move-- where thev tool is located.

In actualcoperation this cleaning procedure is carried out through theentire length of the perforated casing and after such cleaning operationhas lbeen completed thewater locating apparatus of any conventional typesuch as iaf chemical, electrical or photoelectric Watei/ Witch islowered into the perforated casing and the zone or zones of waterintrusion are located.v 55

Assuming conditions such as are ill trated fin g Figs. 1 and 2, thiswater locating ap ratus will establish the limits of the water zo e asbeing/ between the points A and B of Fig. 2. g' y As is well known tolthose famil ar with the/60 art, most of the conventional nerforated/"crstrainer casings are provided with' perforations in the form of smallIslots or open gs equipped. with buttons, such buttons being i rovidedI`with small slots and in lthe' event this is the' type of casing withwhich the process is being carried out, it is desirable in order tosecure the most positive results. to provide the region of the casingwall in which the water intrusion isto be 70 which a cement slurry canbe readily forced into the formation from the interior of theaslng.

For the purpose of providing these enlarged perforations anyconventional casing perforator may be employed. Fig. 3 illustrates theDerfo- 75 vper end. The blade is adapted to be swung outwardly intoperforating engagement with the casing through the medium of a tonguemember 34 which is slidably and pivotally mounted in v, the lower endportion of the groove, such tongue member being actuated during downwardmovement of the body by means of a releasable anchor member generallyindicated by reference numeral 35. This anchor member carries a tailpiece 36 slidably mounted on a mandrel 31 and adapted to be latchedagainst movement with respect thereto. 'I'he upper end of the mandrel 31carries a wedge block or shoe 38 positioned behind the tongue 34 andadapted to wedge the same against the wall of the casing when the tailpiece is latched to the mandrel and `the'fbody is moved downwardlyrelative to the tail piece. The tongue is provided with a casinggripping member in the form of a serrated Wheel indicated at 39; As waspointed out above the particular perforating tool forms no part of thepresent invention and for a more complete description of itsconstruction and operation, reference is made to the co-pendingapplication of Robert S. Smith, Serial No. 76,567, filed April 2'?,1936, now matured into Patent No. 2,046,752,

. dated July 7, 1936, which is assigned to the assignee of the presentapplication.

In the perforating step, which, as will be understood by those familiarwith the art may be eliminated in the event the perforated pipe orcasing is of a character such that cement slurry will readily flowthrough the openings therein, it is preferable that the perforations bestarted at a point slightly below the lower extremity B of the zone ofwater intrusion and that they be carried to a point slightly above theupper extremity A of such zone, these enlarged perforations beingindicated generally by reference numeral-40 in Fig. 3.

As was pointed out above, it is a principal object of this invention toprovide a process in which the water sand or zone of water intrusion canbe positively isolated from the oil sand in the region outside-of theperforated casing prior to the closing off of the perforations Withinthe casing in the actual Water zone. In other words, my inventioncontemplates as one of its primary objects the placement or provision ofwhat I may term bridges which surround the perforated casing and aresealed or locked in the formation at the two extremities of the waterzone. The placement of these bridges is accomplished preferably by firstinstalling a plug member 50 within the casing at a point below the lowerextremity of the water zone and then supplying cement in anyconventional way into the casing above this plug, such cement beingsupplied in a manner such that it is discharged through the perforationsof the casing and is forced out into the formation forming a cement plugI within the casing and a cement bridge 52 which surrounds the casing inthe oil shale adjacent the water sand. After this plug has beeninstalled, a second plug 53 is placed within the casing at the upperextremity of the water sand which is followed by the installation of acement plug 54 and an encasing cement bridge 55 which surrounds theperforated casing in the oil shale.

After the cement plugs and bridges 54 and 55 have had an opportunity toset, the cement plug 54 and its supporting plug 53 are drilled from theinterior of the casing by means of any suitable drilling apparatus Whichleaves the casing open down to the plug 5I and leaves the portion of theperforated casing at the upper extremity of the water zone encased in acement bridge 55 preferably of substantial length, which positivelyseals that portion of thebore hole which extends through the oil shaleabove the bridge from the water sand. The oil shale below the water sandis correspondingly` sealed by the bridge 52. 'Ihe result of thisoperation is illustrated in Fig. 5, and the next step in the operationentails the placement of cement within that portion of the casing whichoccupies the water sand under sufficient pressure to completely encasethe casing with cement thereby preventing water intrusion. The bridge 55serves a purpose additional to that pointed out above in that it may beused to prevent the migration of cement slurry back into the perforatedcasing at a point above the Water zone where it might cause thecementing apparatus to be frozen in the casing or where it might serveto plug the perforations in the region of the oil zone which must bekept clear in order to obtain the maximum oil p'roduction.

In Fig. 6 I show a preferred form of apparatus which may be employed forperforming the nal cementing operation, such apparatus being designed tomaintain at a minimum the migration of cement back into the casing fromthe water zone. This apparatus consists of a cement dis-l charge conduit60 having discharge openings 6|v at its lower end, such conduit beingprovided with a plurality of spaced packers 62 starting from a pointimmediately above the discharge end 6| and extending at predeterminedspaced intervals throughout the full length of the discharge conduit 60.The discharge conduit 60 is formed of a lengthslightly greater than thedistance between the two bridges 55 and 52 and the distance between thesuccessive packers 62 is slightly less than the length of the bridge 55as observed by the operator when it was installed.

The upper end of the discharge conduit 60 is connected with a fitting 64which in turn is connected to a cement delivery pipe 65. The fitting 64is provided with a valve seat 66 which is associated with a valve 61mounted on the lower end of a Valve stem 68 which is slidably supportedin a spider 69 and is biased'toward a closed position by means of acompression spring 10. The upper end of this valve stem is adapted to beengaged by a valve opening stem 1I which is mounted on a spider 12 inthe bottom of the tubing 65. With this arrangement it will be seen thatthe valve may be opened and closed by rotating the tubing 65 in itsthreads 13 whereby it is attached to the box in theupper'endof thefitting 64. Reference numeral 15 indicates an inwardly opening checkvalve whichv is positioned in the bottom portion of the tubing 65, thepurpose of which will appear from the description of the operation ofthis cementing tool.v

' discharge end rests on the bottom bridge 5l.

wardly through a tubing 65. 'Ihe cement discharging assembly is lowereddown within the casing to the position shown in Fig. 6 at which its Acement slurry of suitable consistency and under a substantialpressure'is then delivered into the these packing members is alwayscontained in the region of the casing surrounded by the bridge 55,thereby maintaining a positive pressure seal between the zonesurrounding the region of the casing in which the cement is beingapplied and the region of the perforated casing above the bridge 55.Since the bridge 55 prevents the migration of cement slurry upwardlyalong the bore hole into the oil shale it will be seen-that the packingmembers 62 sealing the interior of the casing in the manner justdescribed, co-operate with the bridge to prevent the migration of cementinto the region above the bridge 55 through the interior of the casing.

This cement dischargingy operation is carriedl on until the deliveryconduit has been raised a distance corresponding to the distance betweenthe two bridges. When this has been accomplished the conduit 55 isrotated to unscrew the threads 13 a suflicient amount to permit theclosure ofthe valve 61 whereby the cement plug so installed is heldunder pressure.

In order to insure the removal of any cement slurry which may possiblyhave leaked into the perforated casing above the uppermost packer,

I consider it preferable to next circulate a washing fluid, such as mudor the like, downwardly through the casingfrom the surface of theground.'such fluid being returned with any cement slurry which may` haveaccumulated therein through the bypass valve 65. After this has beendone and the desired time has elapsed, the cementing tool is vthenwithdrawn from the well, leaving the region of the perforated casingwhich occupies the water sand completely filled with a cement plug andvcompletely surrounded with a wall or. encasement of cement which hasbeen forced out into the formation under a substantial pressure.

The next operation in the event the water zone is situated between twoportions of oil producing Ashale or sand, is to drill the cement fromthe interior of the casing thereby leaving an open pipe provided withperforations in the oil zone to be encased with a water impervious wallof cement 18 in the region of the water zone.

Fig. 8 shows a modified form of cementing apparatus which is preferablydesigned/ for use where the water intrusion is taking place at thebottom of the hole, since this apparatus ls one in which no particularprecautions are taken to prevent the return of cement slurry into thecasing around the cement discharge conduit. 'I'his apparatus is shown ascomprising a cement discharge conduit 80 having a guide shoe 8| at itslower end and provided with a packing member frozen in the casing 'attheV end of the cementing operation. In the event the zone or region ofWater intrusion is at the bottom of the hole, it will be the practice tomerely unscrew the conduit 81 from the fitting 86 and leave the remaindev of the tool in the well. In the event this type of apparatus is usedfor shutting oi intermediate water intrusion.'l it will in the event itbecomes frozen in the hole, be necessary to remove it from the casing bya milling operation. Bearing this point in mind, it will be seen thatother types of apparatus may be employed for delivering the cement intothe casing but to facilitate the removal of the tool and the delivery ofcement into the desired zone under a substantial pressure, I consider:it preferable to use an apparatus of the type shown and described inconnection with Fig. 6 which emb odies features of novelty that areclaimed as a part of this invention.

It will be understood that while I have herein described and illustratedone preferred procedure contemplated by this invention, that varioussteps of the procedure may be eliminated depending upon the type ofcasing used and the well conditions encountered, also that while I haveherein described and illustrated certain preferred forms of apparatus tobe used in the practice ofthis process, that other types of apparatusmay be used without departing from the scope of the invention asyexpressed in the appended claims.

I claim as my invention:

1. A method for shutting oi intrusion from a water zone through theperforated casing of an oil well which includes: placing a cement plugand bridge in and around said casing at the lower extremityl of saidwater zone; surrounding saidcasing with a cement bridge at the upperextremity of said water zone; discharging cement under pressure withinsaid perforated casing'near said bottom plug and bridge; and graduallyraising the point of discharge of said cement at the same timemaintaining a seal within said casing in the region of said upperbridge.

2. A method for shutting off intrusion from a. l l

' the point of discharge of said cement at the same time maintaining aseal within said casing in the region of said upper bridge-thereby llingand surrounding the casing with cement in the region of said water zone;and drilling the cement from lthe interior of said casing after it hasset.

3. A method of shutting off intrusion from a water zone through theperforated casing of an oil well which includes: locating vthe upper andlower limits of said water zone; forming a plurality of openperforations in said casing in the region of said water zone; formingcement bridges in the formation surrounding said casing atl the twoextremities of said water zone; and forcing cement under pressure intosaid casing and the formation surrounding same between said bridges.A

"4. A method of shutting oif intrusion from a water zone through theperforated casing of an oil well which includes: locating the upper andlower limits of saidv water zone; forming a plurality of openperforations in said casing in the region of said water zone; formingcement bridges in the formation surrounding said casing; forcing cementunder pressure into said casing and the formation surrounding samebetween said.

bridges and drilling thev cement from the interior of said casing afterit has set.

5. A method of shutting off intrusion from a water zone through theperforated casing of an oil well which includes: locating the upper andlower limits of said water zone; forming a plurality of openperforations in said casing in the region of said water zone; formingcement bridges in the formation surrounding said casing at the twoextremities of said water zone; forcing cement under pressure into saidcasing and the formation surrounding same between said bridges;maintaining a seal within said casing in the ref gion of said upperbridge during said last men- 6. A method of shutting off water intrusionthrough the perforated casing of an oil well which includes the stepsof: cleaning the perforations in said casing; locating the upper andlower extremities of the region of water intrusion through saidperforations, forming cement bridges in the formation surrounding saidcasing at the two extremities of said region of water intrusion; andforcing cement under pressure into said casing and the formationsurrounding same between said bridges.

7. A method of shutting off water intrusion through the perforatedcasing of an oil well which includes the steps of cleaning theperforations in said casing-locating the upper and lower extremities ofthe region of water intrusion through said perforations, forming cementbridges in the formation surrounding said casing at the two extremitiesof said region of water intrusion; forcing cement under pressure intosaid casing and the formation surrounding same between said bridges;maintaining a seal in said casing in the region of the upper bridgeduring said last mentioned cementing operation; and drilling the cementfrom the interior of said casing after it has set.

8. A method of shutting olf Water intrusion through the perforatedcasing of an oil well which includes the steps of cleaning theperforations in said casing; locating the upper and lower extremities ofthe region of water intruf sion through said perforations; forming aplurality of large perforations in the Wall of said casing in saidregion of water intrusion; forming cement bridges in the formationsurrounding said casing at the two extremities of said region of waterintrusion; forcing cement underpressure into the casing and theformation surrounding same between said bridges; maintainig a sealwithin said casing in the lregion of the upper bridge during said lastmentioned cementing operation; and drilling the cement from the interiorof said casing after it has set.

9. A method of shutting oif water intrusion through the perforatedcasing of an oil well which includes the steps of cleaning theperforations in said casing; locating the upper and lower extremities ofthe region of water intrusionthrough said perforations, forming cementbridges in the formation surrounding said casing at the two extremitiesof said region of water intrusion; forcing cement 'under pressure intosaid casing and the formation between said bridges; thereby illling suchregion of the casing and the surrounding formation with cement;maintaining a packing seal in said casing above the point of cementdischarge during said last mentioned cementing operation; and then backcirculating a washing fluid down through said casing and up through aninternal conduit after said cement has been installed.

10. A method of shutting off intrusion from a water zone through theperforated casing of an oil well which includes: locating the upper andlower limits of said water zone; foiminga plurality of open perforationsin said casing in the region of said water zone; forming cement bridgesin the formation surrounding said'casing at the two extremities of saidwater zone; forcing cement under pressure into said casin'g and theformation surrounding same between saidbridges through a cement deliverytubingl extending from the surface of the ground; and

maintaining a packing seal between said delivery tubing and said casingin the region of said upper bridge during said last mentioned cementingoperation.

11. A method of shutting off intrusion from a water zone through theperforated casing of an oil well which includes; locating the upper andlower limits of said water zone; forming a plurality of openperforations in said casing in the region of said water zone; formingcement bridges in the formation surrounding said casing at the twoextremities of said water zone; forcing cement under pressure into saidcasing and thel formation surrounding same between said bridges througha cement delivery tubing extending from the surface of the ground;maintaining a packing seal between said delivery tubing and said casingin the region of said upper bridge during saidlast mentioned cementingoperation and circulating a washing uid down through said casing and upthrough said delivery tubin'gin the region above said seal after vsaidlast mentioned cementing operation.

12. For use in supplying cement under pressure to the interior of aperforated casing for the purposes described: an elongated tubing havinga cement outlet at its lower end; a plurality y of packing membersmounted on said tube above said outlet in predetermined spaced relationwith each other; conduit means for delivering cement into the upper endof said tube; a valve in the upper end of said tube; and means operableby relative rotation between said delivery conduit and said tube foractuating said valve.

13. For use in supplying cement under pressure to the interior of aperforated casing for the purposes described: an elongated tubing havinga cement outlet at its lower end; a plurality of packing members mountedon said tbe above said outlet in predetermined spaced relation with eachother; conduit means for delivering cement into the upper end of saidtube; a valve in the upper end of said tube; means operable by relativerotation between said delivery conduity and said tube for actuating saidvalve;

. and an inwardly opening check valve mounted OLNEY P. YOWEML.

